This is a patch we are using on our server for image_attach. It does two things: First, it allows you to attach existing image nodes instead of uploading new images. Second, it provides direct image_gallery integration if image_gallery is enabled. When uploading a new image, you have the option to choose which gallery to assign it to. And, when attaching and existing image, the selection is gallery-aware. Thumbnail previews are shown of all existing images.

I use the image_assit module with the image module so I am a bit confused as to what this patch is actually supposed to accomplish when the said functionality already exists
Also how does image_attach work. I downloaded the updated module but dont really know how to use it to attach existing image nodes or atleast I couldnt see anything whiel trying to create a page or an image

I got like 3 out of 5 failed patches, so I guess the module has updated a bit since june...
I also tried patching with v1.47, but that messed everything up since the main module probably has changed too much.

Probably whichever was latest at the time -- your only guide will be CVS as this is what patches should be against.
If you need this functionality, rather than find an old version to apply the patch to, a better use of your time would be to reroll the patch to the latest CVS head and share it here for other users to review, so I can then commit it!

This is very easy to do already using img_assist. Simply add that module, enable it for your tinyMCE as a button and it will allow you to not only browse all images in the system but also only images that you yourself uploaded.
If the image isn't in the system img_assist will allow you to upload a new one and with the use of taxonomy and image galleries you can not only upload it but specify which galleries it goes into.